1. Field of the Invention
This invention relates generally to an energy storage device, and more particularly, to an electrical storage battery useful in medical devices and a method for manufacturing the same.
2. Description of the Related Art
Electrical storage batteries are in use in a wide range of applications. As improved battery technology allows battery use in more and more demanding applications, the requirements imposed on the batteries"" physical construction increase as well. For example, new battery technologies have yielded small and lightweight batteries with long storage lives and high energy output capabilities. As the size of these batteries has decreased, an expanded range of applications has developed, including many in which the battery is implanted along with an associated battery powered device inside the body of a human patient. These devices are now used to monitor and treat human disease conditions and to maintain normal body functioning in a variety of applications.
Batteries for medical devices are subject to very exacting requirements, such as a long useful life, high power output, low self-discharge rate, compact size, high robustness and reliability over a long time, compatibility with the patient""s internal body chemistry, highly reliable sealing components, etc. In addition, the manufacture and assembly of the batteries should be as simple and low-cost as possible.
The present invention is directed to an energy storage device, more specifically to an electrical storage battery assembly, and related manufacturing method that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an energy storage devices and manufacturing method that will provide devices that having a reliable, secure, and robust construction, and that are suitable for use in medical devices.
Additional features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.
The energy storage device according to the present invention generally includes a case, an electrode assembly disposed within the case, a cover disposed to cover the opening of the case, and a terminal structure attached to the cover.
In one aspect of the present invention, the cover is provided with a hole having a counter bore structure, and the terminal structure includes a gasket made of an insulating material and fittingly disposed within the hole and the counter bore, an under cover insulator member disposed below an under side of the cover, the insulator member defining a hole corresponding to the hole in the cover, a washer made of a conductive material and electrically connected to one of the electrode members of the electrode assembly, the washer being disposed below the insulator member and defining a hole corresponding to the hole in the cover, and a fastening device made of a conductive material and having a shaft passing through the gasket and the holes in the insulator member and the washer, the fastening device applying a pressure in an axial direction of the hole in the cover to press the gasket, the cover, the insulator and the washer against each other to form a seal, the fastening device being electrically connected to the washer and electrically insulated from the cover. Sealing rings may be provided between the gasket and the fastening device or between the gasket and the cover to provide a better seal.
In another aspect of the invention, the terminal structure uses a fastening device that is made of stainless steel.
In another aspect of the invention, the cover is provided with a hole (fill hole) having a counter bore structure, and a plug (fill plug) is fittingly disposed in the counter bore of the hole and fixed to the cover to seal the hole.
In another aspect of the invention, the cover is made of aluminum and electrically connected to one of the electrode members of the electrode assembly, and a disk-shaped aluminum plug (fill plug) is provided to seal a hole (fill hole) in the cover, the plug having a layer of a second metal or metal alloy formed on a top surface thereof and electrically connected to the aluminum to form a terminal of the energy storage device.
In another aspect of the invention, the cover has a first and a second hole, wherein the cover has a symmetrical shape and wherein the first and second holes are located symmetrically with respect to the cover and have identical shapes and sizes. The first hole has a terminal structure disposed therein to form a terminal of the energy storage device, and the second hole (fill hole) has a plug (fill plug) disposed therein to seal the hole.
In another aspect of the invention, the periphery of the cover or the rim of the case is provided with a cutaway portion that forms a step feature.
In another aspect of the invention, the electrode assembly including a mandrel and the electrode members are wound around the mandrel to form a roll. The mandrel is electrically connected to one of the electrode members. The mandrel is made from a metal plate having a center portion and two bent portions forming an S-shape, the bent portions exerting a spring tension on the rolled electrode assembly. The energy storage device may further include a conductive terminal connector with a tab portion forming a spring structure that is inserted into the mandrel in a space between the center portion and one of the bent portions of the mandrel. A base portion of the terminal connector is fixed to and electrically connected to the terminal structure.
In another aspect of the invention, an adhesive insulating film is disposed in the case to insulate a bottom of the case from a bottom part of the electrode assembly, the adhesive insulating film being adhered to either the bottom of the case of the bottom of the electrode assembly.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.